This invention relates to a decanter centrifuge, comprising an elongate bowl, a bearing at each end of the bowl supporting the bowl for rotation about its longitudinal axis, a stationary support means for supporting each bearing, a conveyor screw located within the bowl and journalled for rotation about the axis of the bowl, drive means for rotating the bowl, and differential drive means for causing the conveyor screw to rotate relative to the bowl.
As well-known in the art, a decanter centrifuge is employed for separating a raw material supplied to the interior of the bowl into a solids phase and one or more liquid phases which are withdrawn from the bowl through separate outlets. As a consequence of the rotation of the conveyor screw relative to the wall of the bowl the solids phase is conveyed along a conical part of the bowl wall towards an outlet at one end of the bowl. In known decanter centrifuges the permissible rpm of the bowl, which determines the capacity of the centrifuge, is limited by the dynamic bearing loads resulting from unavoidable unbalance of the rotating components. In practice this circumstance implies that the bearings and the support means of the centrifuge have to be made so stiff that the first critical vibration frequency of the centrifuge is about 50 percent higher than its nominal rpm or rate of revolution.